Boron carbide &lpar;B4C&rpar;&comma; a black crystal powder&comma; is smelted from boric acid and powdered carbon in electric furnace under high temperature&period; It is one of the hardest Man-Made materials&period; With Mohs hardness 9&period;36 and microscopic hardness 5400-6300kg&sol;mm²&comma; it is even harder than diamond and cubic boron nitride&period; Its density is 2&period;52g&sol;cm3 and melting point is 2450&comma; Because of its high strength&comma; low density&comma; corrosion resistant&comma; high temperature resistant&comma; low thermal conductivity&comma; high modulus of elasticity&comma; it is an ideal material for a wide variety of applications&period;

It is a good replacement of diamond&period; Boron carbide also possesses the specialty properties of light quality&comma; neutron absorbing&comma; semi-conductivity&comma; etc&period; So it is also used in armed forces and nuclear industry&period; Boron carbide is widely applied as follows&colon; Refractory material&comma; Armor&comma; Nozzle&comma; Honing stones&comma; Metal matrix Metal matrix composites&comma; Ion transfuse&comma; Film layer as well as Grinding&comma; Polishing&comma; Drilling hard metal alloys&comma; jewels&comma; etc&period; Meanwhile&comma; it is main materials for the wear-resisting parts&comma; precise meter-age element&comma; precise spray nozzle&comma; sealed washer&comma; smelting boron steel&comma; boron alloy&comma; etc&period; Boron carbide has showed many better properties of physics and chemistry in the hi-science&sol;technology field&period;